Glue and method for making plywood



Patented Dec. 27, 1932 HENRY V. DUNf EAM, F BAINBRIDGE, NEW YORK GLUE AND METHOD FOR. MARIN G PLYWOOD No Drawing.

This .invention has for its object the making at a glue or adhesive suitable for use in gluing'together wood objects and the like and particularly wood veneers by processes known in the art and this adhesive is suitable for use where theso-called hot plate process is employed in which heat and pressure are-used simultaneously in joining the several plies or parts to be joined. In the m hot plate process type of gluing the usual method is to dissolve dry blood or blood albumin in water and to apply this dissolved material to wood such as veneers for the purpose of making three-ply panels or other 'multi-ply panels by applying the glue in the usual manner well known in the art of plywood manufacture. When the solution of blood or, albumin has been applied to the veneers and the latter assembled to constitute the panels they are. placed in hydraulic presses which are equipped with steam heated platens. -As a general thing about three glued up panels are. placed between each set of platens and from 300 to 500.pounds per square inch of pressure applied for from 3 to 5 minutes. The temperature of the heated platens may be about 250 F. or in some cases somewhat higher.

When pressed between hot plates in this manner, the panels become heated'up somewhat. Even when three three-ply panels are pressed between the two hot plates, the inner panel becomes hot enough to be uncomfortable to handle. During this treatment, the glue joint becomes .hot enough to coagulate the albumin and to set the glue. Perhaps steam generated in the hot pressing may assist in this.

By this procedure the glued panels ob- 0 tain'ed have a good d'ry strength and due to the heat applied to the liquid blood there is a coagulation of the albumin to such an extent that the lued panels will not separate easily when soa ed in water. Such ,types of glued woods are employed in airplane construction and other commercial lines of manufacture where good water-resistance is desired.

There are, however, certain objections to 1 the use of blood albumin for this type of gluing. In the first place it is quite expenglued surface.

Application filed September 24, 1929. SeriaI No. 394,925.

face, particularly on some types of soft woods such as poplar, pine, fir, and the like. By my invention I have found that I can secure an improved blood albumin glue particularly suitable for ,hot plate press work, which will remain usable longer than blood albumin, will have a better flow when appied to panels and the like, and will give a more uniform layer of film of glue on the To obtain these results I mix withthe blood albumin the desired quantities of mixtures of finely ground seed meal and alkali or casein, alkali and a finely ground seed-meal containing a relatively high percentage of-protein.

In order to more fully describe andexplain my invention I give herewith, examples by way of illustration, and tests showing several combinations which have proved to be satisfacto y although I do not limit myself to the ex$ples and proportions cited. I

In referring ,to blood or blood albumin I mean dried blood or what is known and sold commercially as dried blood albumin. Obviously the blood orblood albumin could be used in the undried condition although this is not usually practical due to the rapiddecomposition of the blood in this form.

In referring to casein, I mean a dried milk casein of ordinary commercial grade, preferably ground to pass a 50 mesh standard wire screen or finer.

In referring to seed-meals I mean the meal from protein-rich seeds, such as the of peanut; cotton-seed, soy bean and the like, which have been finely ground'preferably so that practically all of the meal will pass throughan 80 mesh standard wire sieve and preferably a meal or flour made from thepress cake of the seed, after the major portion of the oil or fat has been extracted or removed by the usualcommercial process employed in extracting or expressing the hatural oil content of the seeds.- These seed I Example 1 90 parts of blood albumin, 30 parts of casein, 30 parts of peanut meal, 100 parts of sawdust. These ingredients are preferably mixed together dry and are added to 600' parts of cold water and slowly mixed for from minutes to half an hour. Then another 600 parts of cold water are added, the mass well mixed and allowed to stand for 1 hour. At the end of the hour I add 36 parts of commercial hydrated lime previously mixed in 54 parts of water. I then mix for about five minutes, then add 5 parts of sodium silicate, mix another 5 minutes when the glue is ready to be used.

Ewample 2 90 parts of blood albumin, 15 parts of casein, 45 parts of peanut meal, 100 parts of sawdust, preferably mixed together dry and proceed as in Example 1. Ewample 3 90 parts of blood albumin, 15 parts of casein, 45 parts of peanut meal, 5 parts of tri-sodium phosphate, 100 parts of sawdust,

mixed together dry and proceed as in Example 1, (including the addition of lime and sodium silicate).

Ewample 4 90 parts blood albumin, 60 parts-soybean meal, 5 parts tri-sodium phosphate, 2 parts sodium fluoride, 100 parts sawdust. Mix

together dry and proceed as in Example 1.

I am of course aware that blood albumin and alkalies have been used in adhesives, and

make noclaim thereto. Also casein and seedmealshave been used with alkali. But, as

I have clearly demonstrated by actual tests, there is an unexpected coaction between the constituents of this compound glue. To illustrate this, I cite an experiment made with the identical mixture of Example 1, above, but omitting the casein and peanut meal. The glue could be mixed exactly in accordance with that example. However within a few minutes afterthe completion of the mixing, the glue became so thick as tobe no longer spreadable by an ordinary glue spreading machine. With the casein and '6 peanut meal added, as per Example 1, the

glue was spreadable upon the glue machine or about two hours.

Stated otherwise, the glue made from blood albumin, sawdust, lime, sodium silicate and water would be impractical since it has a life of only a few minutes, whereas when the casein and peanut meal are added, the life is about two hours. This first would be impractical for use on a spreading maclhine, whereas the later would be practica With the glues prepared as per Examples 2 and 3, above, the life will vary between 1.5 and 3 hours, more or less, depending on proportions, etc. With Example 4, a still thinner glue is formed, suitable for some types of plywood, which does not thicken for a longer time than the other examples above.

Obviously other combinations of these ingredients may be made and varying proportions employed depending upon the type of wood that is to be glued and other features well known in the art of the gluing of wood.

In the above formulas, I can use other alkaline salts of alkali metals (say sodium carbonate, di-sodium phosphate, etc.) in place of the tri-sodium phosphate. In using caustic soda, this will ordinarily be added to the Water used in making up the liquid glue, or it can be added with the lime. The lime and sodium salts would seem to react on mixing with water.

The sawdust used can be hardwood or softwood sawdust, preferably ground to pass a 40 mesh screen, or finer. It might be as fine as the seedmeal or flour, or finer. Equivalent materials such as corn cobs, chaff from grain, hulls from seeds, ground peanut shells, or the like, can be substituted. Sawdust and equivalent material will hereinafter be included in the term cellulosic material. I

For securing the strongest joints I prefer to use some casein at least in, the formula. Even a small amount improves the product somewhat. Where very soft woods are employed and only relatively waterproof results For instance the blood albumin, casein, and

seed-meal, with or without sawdust, could be made and sold by the glue manufacturer,

with instructions on the package as to addingthe other components, to be added by theuser. Likewise the casein and seed-meal,

with or without the dry lime hydrate and sodium salts and/or blood albumin, could be sold by the glue manufacturer, all as well known in the dry glue industry.

It will be understood that glues of this type are generally sold in the dry state, and only mixed with water to form the liquid glue at the time of use or a few hours, at the most,before use.

The method of applying the glues illustratively given in the above examples is the same as when applying any other glue, as by means of glue rolls or by spreading the glue on the Wood with a brush or by any other desired manner, putting the glued panels in the hydraulic press between the heated platens, applying desired pressure and temperature for a period usually not exceeding 5 minutes, then the panels may be removed, stacked for drying for a few days if desired when they are ready to be used as required.

By following this disclosure I have been able to secure glued wood of a veneer panel type which has shown dry strengths on the Riehle testing machine, (which is a standard testing machine for testing plywood strengths) of as high as 430 pounds per square'inch for the dry strengths and samples of this type of glued wood when soaked in water for 48 hours show no separation even at the edges of the specimen samples and have shown as high as 270 pounds wet strength per square inch after this 48 hour soaking period.

l/Vhile I have particularly described the application of the glue of this invention in the hot plate process, in which the present glue 1s very suitable, it is to be understood that the glue described is not limitedto use in this process.

I claim i ,y

1. A glue base comprising as its essential constituents blood albumin, seed-meal rich in protein, and casein, which base upon m1xing with water, alkali and an alkaline earth can produce a glue suitable for making waterproof plywood.

2. A glue base comprising blood albumin, seed-meal rich in protein, and casein, and cellulosic material, which base upon mixing with water, alkali and an alkaline earth can produce a glue suitable for making water-. proof plywood.

3. A glue comprising as its essential constituents the reaction products of blood albumin, seed-meal of high protein content, alkali and water, such glue being substantially free from added rubber and from formaldehyde material.

4. A glue comprising as its essential constituents the reaction products of blood albumin, seed-meal of high protein content, casein, lime, alkali and water.

5. A glue comprising the reaction products of blood albumin, seed-meal of high protein content, cellulosic material, alkali and water,

such glue being free from rubber and from formaldehyde and itscompounds.

greater than any one of said named ma-.

terials, alkali and water.

8. A glue comprising the reaction products of blood albumin, seed-meal of high protein content, casein, lime, alkali and water, and a comminuted cellulosic material constituting the largest solid ingredient.

9. A glue comprising the reaction products of blood albumin, seed-meal of high protein content, casein, lime, alkali and water, said glue having a life several times greater than the life of a glue with the corresponding proportion of blood albumin, lime and alkali, but without the casein and seed meal added.

10. A glue comprising the reaction products of blood albumin, seed-meal of high protein content, cellulosic material, said cellulosic material being in amount greater than any of said mentioned material, alkali and water.

11. A glue base comprising 90 parts of dried blood albumin, 15 to 30 parts of dried milk casein, 30 to 45 parts of highly proteinaceous seed meal and about parts of fine com- 

